Heat transfer sheet assembly with an intermediate spacing feature

Abstract

A heat transfer sheet assembly for a rotary regenerative heat exchanger has first and second heat transfer sheet elements stacked one against the other with a first repeat of a first profile on one sheet element opposing a second repeat of a second profile on the other sheet element. The sheet elements are spaced apart by a plurality of wide-gauged parallel sheet spacing features of the first profile repeat RI of the second profile repeat to form a generally close sided elongate channel for gaseous flow therethrough. The second profile of repeat includes an elongate fifth sheet spacing feature in the form of a lobe contacting undulations of the adjacent first profile of repeat.

What is claimed is: 
     
       1. A heat transfer sheet assembly for a rotary regenerative heat exchanger, comprising:
 a first sheet element having a first profile comprising a plurality of parallel and elongate first and second sheet spacing features extending longitudinally in a gaseous flow direction, with a first repeat of said first profile being defined by and including the first and second sheet spacing features and a portion of the first sheet element extending between the first and second sheet spacing features; and 
 a second sheet element of a length equivalent to the first sheet element, the second sheet element having a second profile comprising a complementary plurality of parallel and elongate third and fourth sheet spacing features with a second repeat of said second profile being defined by and including the third and fourth sheet spacing features and a portion of the second sheet element extending between the third and fourth sheet spacing features, 
 the first sheet element being packed against the second sheet element with said first and third sheet spacing features seating against one another and the second and fourth sheet spacing features seating against one another, wherein the seated first and third sheet spacing features and the second and fourth sheet spacing features define a generally close sided elongate channel for gaseous flow therethrough, 
 the first sheet element having lobular heat transfer undulations extending laterally and uninterrupted in between each of the first and second spacing features, 
 the second sheet element further comprising an elongate fifth sheet spacing feature extending longitudinally along at least half a length of the second sheet element, intermediate each of the third and fourth sheet spacing features, the fifth sheet spacing feature comprising a lobe contacting at least some of the lobular heat transfer undulations between the first and second sheet spacing features of the first sheet element, the lobe of the fifth sheet spacing feature having an amplitude less than or equal to a spacing provided by the seated first and third sheet spacing features and the seated second and fourth sheet spacing features. 
 
     
     
       2. A heat transfer sheet assembly in accordance with  claim 1 , wherein each of the first sheet spacing features comprises a lobe extending away from a nominal plane of the first sheet element; and
 each of the third sheet spacing features comprises a flat in a nominal plane of the second sheet element. 
 
     
     
       3. A heat transfer sheet assembly in accordance with  claim 1 , wherein each of the second sheet spacing features comprises a lobe extending away from a nominal plane of the first sheet element; and
 each of the fourth sheet spacing features comprises a flat in a nominal plane of the second sheet element. 
 
     
     
       4. A heat transfer sheet assembly in accordance with  claim 1 , wherein each of the fifth sheet spacing features comprises a notch extending the length of the second sheet element and having the lobe extending away from a nominal plane of the second sheet element toward the said first sheet element and a second lobe extending in the opposite direction away from the first sheet element with the two lobes connected by a flat sheet section. 
     
     
       5. A heat transfer sheet assembly in accordance with  claim 1 , wherein each of the fifth sheet spacing features extends the length of the second sheet element and comprises a first elongate section having the lobe or a notch extending away from a central plane of the second sheet toward the first sheet element adjacent at least one second elongate section wherein opposing ends of the first and second elongate sections are connected to one another. 
     
     
       6. A heat transfer sheet assembly in accordance with  claim 5 , wherein each of the at least one second elongate sections comprises a lobe extending away from the central plane of the second sheet element oppositely to the first elongate section lobe. 
     
     
       7. A heat transfer sheet assembly in accordance with  claim 1 , wherein the second sheet element further comprises lobular heat transfer undulations extending laterally and uninterrupted respectively between the third and fifth sheet spacing features and the fifth and fourth sheet spacing features. 
     
     
       8. A heat transfer sheet assembly in accordance with  claim 7 , wherein the undulations of the first sheet element run oblique to the undulations of the second sheet element. 
     
     
       9. A heat transfer sheet comprising:
 a sheet element comprising a plurality of features extending longitudinally in a gaseous flow direction, the plurality of features comprising: lobular sheet spacing features, flat sheet spacing features, and undulated planar heat transfer portions, 
 wherein the sheet element comprises a first repeat and a second repeat, the first repeat comprising:
 a first flat sheet spacing feature; 
 a first undulated planar heat transfer portion immediately adjacent the first flat sheet spacing feature; and 
 a first lobular sheet spacing feature immediately adjacent the first undulated planar heat transfer portion, 
 
 the second repeat comprising: 
  the first lobular sheet spacing feature; 
  a second undulated planar heat transfer portion immediately adjacent the first lobular sheet spacing feature; 
  a second lobular sheet spacing feature immediately adjacent the second undulated planar heat transfer portion; 
  a third undulated planar heat transfer portion immediately adjacent the second lobular sheet spacing feature; and 
  a second flat sheet spacing feature immediately adjacent the third undulated planar heat transfer, 
 
       the first repeat and the second repeat alternating transversely along a width of the sheet element. 
     
     
       10. A heat transfer sheet assembly comprising:
 a first sheet element in accordance with the sheet elements of  claim 9 ; and 
 a second sheet element in accordance with the sheet element of  claim 9 , 
 the first sheet element aligned with the second sheet element such that a first repeat positioned on the first sheet element is opposite a corresponding second repeat positioned on the second sheet element. 
 
     
     
       11. A heat transfer sheet assembly in accordance with  claim 10 , wherein each of the first sheet element and the second sheet element has a front face and a back face available for heat transfer, with the front face of the first sheet element opposing and in part contacting the back face of the second sheet element. 
     
     
       12. A heat transfer sheet assembly in accordance with  claim 9 , wherein:
 undulations of the first undulated planar heat transfer portion extend obliquely and uninterrupted between the first flat sheet spacing feature and the first lobular sheet spacing feature, 
 undulations of the second undulated planar heat transfer portion extend obliquely and uninterrupted between the first lobular sheet spacing feature and the second lobular sheet spacing feature, 
 undulations of the third undulated planar heat transfer portion extend obliquely and uninterrupted between the second lobular sheet spacing feature and the second flat sheet spacing feature. 
 
     
     
       13. A heat transfer sheet assembly in accordance with  claim 12 , wherein the undulations of the first undulated planar heat transfer portion extend in a first direction and undulations of the second undulated planar heat transfer portion and the third undulated planar heat transfer portion extend in a second direction different from the first direction. 
     
     
       14. A heat transfer sheet assembly in accordance with  claim 1 , comprising a multiplicity of first sheet elements and second sheet elements stacked in a basket and sandwiched between two support sheets with heat transfer undulations extending outwardly from the sheet elements immediately adjacent a respective support sheet contacting the respective support sheet at support points spaced apart laterally by about 57 to 76 mm (2.25 to 3 inches). 
     
     
       15. A heat transfer sheet assembly is accordance with  claim 10 , wherein:
 the first flat sheet spacing feature of the first repeat positioned on the first sheet element is seated against the first lobular sheet spacing feature of the second repeat positioned on the second sheet element, 
 each second repeat positioned on the first sheet element is opposite a corresponding first repeat positioned on the second heat transfer element such that:
 (a) the first lobular sheet spacing feature of the second repeat positioned on the first heat transfer element is seated against the first flat sheet spacing feature of the first repeat positioned on the second heat transfer element, and 
 (b) the second lobular sheet spacing feature of the second repeat positioned on the second heat transfer element is opposite the first undulated planar heat transfer portion of the first repeat positioned on the first heat transfer element and bisects a space between the first sheet element and the second sheet element to provide a channel on either side of the second lobular sheet spacing feature.